今次呢，我要講下胸腺 (thymus)。
Hah? What the fuck is thymus, is it eatable? I bet you to have this in your mind. I've already talked about bone, and hematopoiesis, i.e. blood cell formation. This includes leukocytes, i.e. white blood cells (WBCs), formation and thymus is exactly an immune organ related to WBCs.
胸腺？乜撚野胸腺？食得嫁？我敢打賭你一定咁唸😂咁我其實都已經講過骨頭啦，都知道骨頭同造血作用有關，所謂造血作用係唔單止造紅血球，重包埋白血球，而胸腺呢就正正係一個有關白血球製造既免疫系統器官。
Thymus is like a filter, filtering out self-attacking WBCs. However, not all WBCs go through the thymus. Only a special type called the T-lymphocyte (T stands for thymus), a kind of adaptive immunity cell, will go through the filter.
胸腺就好似一個過濾器，過濾一d會攻擊自己既白血球。之但係呢，唔係所有既白血球都由胸腺過濾，只有一隻特別白血球，叫胸腺淋巴球 (T-lymphocyte) 要通過胸腺依舊過濾器。
You may wonder why would we make self-attacking cells. If you want to find out, just read on~
或者你會唔明點解我地個身體會咁on9，整d攻擊自己既細胞，如果你想知點解，睇落去啦～
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Before talking about thymus, we need to locate it first.
睇下胸腺既位置先。
This is where the thymus locates, anterior to the heart and posterior to the sternum.
胸腺位於心臟既前面，胸骨 (sternum) 後面。
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The image shows an overview of the thymus. It has totally 2 lobes.
張圖可以見到成個胸腺既內部結構，我地總共有兩舊胸腺葉。
The thymus can be divided into 3 parts, capsule, cortex and medulla. The naming system quite similar to the kidney, if you remember.
胸腺主要可以分成3個部分，包膜 (capsule)、皮質 (cortex) 同埋髓質 (medulla)。命名既方法同腎都幾似，如果你記得既話。
The capsule is an epithelial layer surrounding the thymus.
包膜就係胸腺最外層既部分。
The cortex is the layer after the capsule, mainly immature T-lymphocytes can be found here.
包膜之後係皮質，依到有好多未成熟既胸腺淋巴球。
The medulla is the central part of the thymus. It is also the site for the maturation of T-lymphocytes.
胸腺既中間部分就叫髓質，依到就係胸腺淋巴球成熟既地方。
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There are mainly 2 kinds of cells in the thymus, the epithelial reticular cells and T-lymphocyte.
胸腺主要有兩種細胞，分別係頭先一直講既胸腺淋巴球同埋網狀上皮細胞 (epithelial reticular cell)。
Epithelial reticular cells are cells that construct the filtering network in the thymic medulla. It also presents self-substances, or self-antigens.
網狀上皮細胞就係過濾網既組成細胞，遍佈成個胸腺髓質。依D細胞會展示自體物質。
T-lymphocytes are adaptive immunity cells originated from the bone marrow.
胸腺淋巴球係運作標靶免疫力 (adaptive immunity) 既細胞，而佢係由來自骨髓既造血幹細胞轉化而成。
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It is time to get an idea of immunity. Although it is not very related to the thymus, but it is important in the understanding of the T-lymphocyte and the reasons for the existence of the thymus.
係時間認識一下免疫力。免疫力依個term我地就成日聽啦，但到底係咩野呢？雖然免疫力同胸腺既關係唔係好直接，但係認識左免疫力可以對有胸腺淋巴球更加好既了解，從而明白依個器官存在既目的。
We have 2 kinds of immunity, innate immunity (or non-specific immunity) and adaptive immunity (or specific immunity).
我地既免疫力主要可以分做兩種，分別係泛用免疫 (innate immunity) 同埋標靶免疫 (adaptive immunity)。
Innate immunity refers to immunity with non-specific targets, i.e. protect us from everything foreign, like our skin and inflammatory response. A wide range of protection means that it is less powerful.
泛用免疫力係指冇特定目標既免疫力，例如皮膚、炎症反應等等，佢地會防止一切對身體唔好既野，但廣泛既防護某程度上都代表住低效力。
Therefore, adaptive immunity is developed, it refers to immunity with specific targets, i.e. protect us from a specific pathogen. It is done by a specific type of cells called lymphocyte, which is a kind of WBC.
所以呢，我地就發展出標靶免疫啦。標靶免疫係指有特定目標既免疫力，基本上就係指由淋巴球 (lymphocyte) 建構出黎既免疫力，依種免疫會集中對付特定既目標。
